


The Rules of Deduction (as observed by Rosie M. Watson)

by togethertheyfightcrime



Category: Sherlock (TV), Sherlock Holmes & Related Fandoms
Genre: 221B Baker Street, Everything is Beautiful and Nothing Hurts, Families of Choice, Family, Family Dynamics, Fluff, Fluff and Humor, Gen, Good Dad John Watson, Humor, John is the dadliest dad, Johnlock - Freeform, Kids say the darndest things, M/M, POV Female Character, Post-Canon, Post-Season/Series 04, Rosamund Mary "Rosie" Watson POV, Rosie POV, Rosie is down for being named Sherlock, Sherlock is the Best Godfather Ever, Sherlock never pays for cabs, Slice of Life, The Rules of Deduction, Unconventional Families, can be read as, deus ex Mary's videos?, everyday life in 221b, everyone is happy goddamnit fight me
Language: English
Status: Completed
Published: 2018-01-14
Updated: 2018-01-14
Packaged: 2019-03-04 21:11:05
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 8,433
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/13373133
Author URL: https://archiveofourown.org/users/togethertheyfightcrime/pseuds/togethertheyfightcrime
Summary: Rosie Watson has a dad who's a doctor and blogs cases. She has a Sherlock who's her godfather and a consulting detective. She has Mrs. Hudson who lives downstairs to not be the housekeeper, and Molly who's a doctor for dead people, and Uncle Mycroft who's the government, and Uncle Greg who brings cases. And they're the best family ever, even though Sherlock's the only one who agrees that Rosie should've been named for him.





	The Rules of Deduction (as observed by Rosie M. Watson)

**Author's Note:**

> Not Britpicked except for what I can recall from trips to London and what the internet can tell me. Comment and let me know if there's anything I need to fix! 
> 
> I've left Rosie's age up to the reader's interpretation just for simplicity's sake – in my mind she's anywhere from an especially clever four to eight or so. This fic can also be read as Johnlock or not, whatever you prefer – partially because it's from Rosie's perspective and as a whatever-year-old I doubt the precise location of her parents' relationship on the sexuality spectrum interests her/matters to her, and mostly because the whole moral of the story is that family is who you love. Sherlock is a dad to Rosie regardless of whether Sherlock and John are gettin' it on.
> 
> I will probably add more to this fic because it was crazy fun to write. If there's anything you'd like to see incorporated into future chapters? companion pieces? please let me know!

The first rule is that you can’t watch the world like you watch telly. When you watch telly you put your brain to sleep and don’t _see_ things, really see things, because telly is for idiots. 

 

“You watch telly sometimes,” Rosie had told Sherlock. 

 

“No, I don’t.”

 

“Yes you do too. The shows about surprise fathers where they get it wrong. And the shows where everyone wants to date the person. And–”

 

“That’s not watching, that’s research. It’s what morons fill their brains with, and my clients are nearly all morons.”

 

Rosie squinted at him. Sherlock didn’t lie to her, but sometimes he only told parts of the truth and made it sound like the whole thing. 

 

The point of the rule was that you have to keep your brain awake so it could really properly look at everything around it. Rosie played the game with Daddy on the tube to school when Daddy was awake enough. Playing the game with Daddy was almost more fun than playing with Sherlock – Sherlock would tell Rosie what she’d got wrong or not seen, so she could get better, but Daddy would muss her hair and say she’s the cleverest girl there is and that Sherlock ought to look out because one day Rosie’ll put him out of a job. 

 

“No I won’t,” she’ll tell Daddy. “Sherlock has to be a detective or you and him can’t pay the rent.”

 

Daddy always laughs at that.

 

* * *

 

Rosie’s real name is Rosamund. It means _rose of the world_ , which doesn’t really make sense, but Daddy and Sherlock say it was her mum’s name. Her mum’s name was also Mary, which is why Rosie’s entire name is Rosamund Mary Watson. 

 

“Why do people have lots of names?” she asked one morning at breakfast. Rosie was in her school uniform and pushing the oatmeal around her bowl so it would look like she’d eaten more of it. Dad was making tea for himself and Sherlock. Sherlock was folded up on his chair in a dressing gown doing thinking. Sherlock always did thinking in the mornings with his eyes shut until Daddy brought him tea. 

 

Daddy said, “Hm? Which people?” 

 

“Me, I have three. So do you, Daddy. And Sherlock has–” Rosie put down the spoon to count on her fingers. “William, Sherlock, Scott, and Holmes is four. Unless I forgot one.”

 

“Nope,” Daddy said, hiding a smile in his cheeks, “that’s the lot.”

 

“So why?”

 

“Well, your mum and I wanted you to have both of her names. And I suppose Sherlock’s parents gave him the other two in case he’d rather not go by Sherlock.”

 

“Did you know, Rosie,” Sherlock called from his chair, “that Sherlock is actually a girl’s name?”

 

Rosie dropped her spoon. “ _Really_?”

 

“No, it isn’t,” said Daddy. “Eat your oatmeal.”

 

“Daddy, you and Mummy could’ve called me _Sherlock_.”

 

Daddy blinked a bit funny. “Well. Well, we thought Rosie suited.”

 

“It coulda been an extra name. Like how Sherlock has four. Rosie Mary Sherlock Watson. We could add it in.”

 

Sherlock's face did the grin that was usually for having solved a murder.

 

Dad said, “It isn’t really a girl’s name. Oatmeal.”

 

Rosie put a tiny spoonful of oatmeal in her mouth. “Sherlock?”

 

Daddy rolled his eyes.

 

“Watson,” said Sherlock.

 

“ _Is_ it a girl’s name?”

 

“Technically,” Sherlock told her, “there’s no such thing as a girl or boy’s name. Just because our culture says _Rosie_ is something only girls can be called doesn’t mean we won’t change our mind later on.”

 

“Oh, my God,” muttered Daddy. 

 

“Hmm,” said Rosie, and did a thinking face. At Daddy’s raised eyebrow, she stuffed more oatmeal in her mouth. In between chewing, she asked, “So can Sherlock be called Rosie too?”

 

* * *

 

So Rosie’s family is like this:

 

Rosie has a daddy who’s a doctor at the surgery and also blogs the cases he does with Sherlock. She has a Sherlock who’s her godfather and a consulting detective. Also, Rosie had a mum named Mary, who’s dead but loved Rosie very much.

 

Because Rosie doesn’t have a mother anymore she has two godmothers. One is Molly who’s a doctor for dead people and has a lot of cats. Two is Mrs. Hudson who’s basically her gran and lives downstairs to not be the housekeeper. 

 

There’s Uncle Mycroft, who’s not actually her uncle but Daddy says she might as well think of him as one. He’s Sherlock’s brother and also the government. When Rosie was little she thought Mycroft was his whole name – Mike Roft. Sometimes Sherlock still teases Mycroft about that. 

 

Also there’s Uncle Greg, who isn’t her real uncle either but is their best police friend and brings lots of cases. Uncle Greg calls her poppet and has big kids of his own, and he talks to Rosie like she’s a grown-up. 

 

Rosie has an aunt named Harry who’s Daddy’s sister, but she doesn’t see Harry very much so Harry only counts a little. Rosie also has Sherlock’s mum and dad, who sneak Rosie sweets and take her on outings in London when they visit to be tourists. Sherlock’s mum is a maths genius and Sherlock’s dad winks at Rosie when everyone’s too busy to notice her.

 

That’s Rosie’s family, but it’s mostly Daddy and Sherlock plus Mrs. Hudson. 

 

* * *

 

“Now, Watson,” Sherlock told her once, very seriously, “this is extremely important. If you ever meet anyone who says they work with my brother, you are to tell them that Mycroft Holmes is your grandfather, and he takes you for ice cream every week even though he’s meant to be on a diet.”

 

Daddy actually fell off his chair, trying to yell at Sherlock while they’re laughing that hard.

 

* * *

 

Most of Rosie’s days go like this:

 

Dad wakes Rosie up for school and makes breakfast before he goes with her on the tube to drop her off. Then Dad goes to be a doctor or he and Sherlock go to do cases. 

 

When Daddy’s busy being a doctor Sherlock picks Rosie up from school, which is brilliant. If Sherlock and Dad are both on a case Molly picks her up and they get chips, or Mrs. Hudson picks her up in her cool car. One time Uncle Mycroft picked her up and they went to a weird place full of old people in suits who didn’t talk and stared at Rosie while she drew pictures on Mycroft’s newspapers. 

 

She didn’t pretend that Mycroft was her grandfather because Daddy said it was mean even though it was funny.

 

After school if Daddy and Sherlock aren’t home, Rosie mostly stays in with Mrs. Hudson and eats biscuits. Rosie’s supposed to do her homework then, but she’s learned a trick: Mrs. Hudson will always tell exciting stories about before she was old if Rosie asks enough times. Mrs. Hudson did a lot of things before she was old that Rosie doesn’t think her dad would want Rosie hearing about, which is why Rosie loves hearing them.

 

If there’s no case on, Sherlock will be home and he’ll complain about Rosie’s homework for her until she gets it done and they can have fun. 

 

Usually fun is experiments, or going to St. Bart’s, or visiting museums so Sherlock can tell her what the plaques got wrong, or playing Cluedo. Sherlock always comes up with a better ending than Cluedo has and then he teaches Rosie to cheat at cards. 

 

Sometimes Sherlock makes up cases or scavenger hunts or puzzles for Rosie to solve so she can practice having a good brain. Sometimes he teaches her dancing and then plays the violin while she practices the steps. Other times Rosie just asks Sherlock every single question she has and he always knows the answer unless he’s deleted it.

 

The thing about Sherlock is that if he cares about something, he knows _everything_ about it. If he doesn’t care about something he doesn’t keep it in his brain. Once Sherlock told Rosie that he’s never deleted anything about her. She hugged him the hardest ever. 

 

If it’s Daddy with her after school then he makes Rosie do her homework first thing after tea. Then he checks it and helps her with what she’s got wrong because doing her best in school is one of Daddy's rules.

 

After homework sometimes they go out and do the shopping so there's food that's not takeaway, or go to the park, or the playground, or go see one of Rosie’s friends, or go to a film. It always puts Sherlock in a strop if they see a film without him, but if they ask him to come along he says the cinema is full of morons and the last time he saw a film he was so bored he started predicting lines before they were spoken and got thrown from the building.

 

If Rosie and Daddy are staying in they read, or have a race for who can tidy their bit of the flat fastest, or practice self-defense which makes Rosie feel like a superhero. Rosie’s allowed an hour on Daddy’s computer for fun but longer if she’s doing some sort of learning, so she spends a lot of time playing games on the educational sites Sherlock finds for her.

 

Sometimes Rosie and Daddy play a game where Daddy starts writing down a story, then Rosie has a go, then Daddy and then Rosie again until the story ends. It’s great fun, even though Rosie knows it’s also a sneaky way to make her practice writing and spelling and all of that. If Sherlock’s in and not distracted (or bored) he sometimes tells Rosie a new word that she’s got to work into her bit of the story. Then when the story's over Sherlock steals it for the giant file on Rosie he's had for forever and that Dad says is mostly pictures of Rosie being cute.

 

When they don’t order in Dad makes dinner and Rosie helps a little until she’s bored and then drifts around the flat and gets into things. Sherlock doesn’t always like eating food but sometimes he and Rosie do a race for who can finish their plate first and start on the HobNobs. 

 

At night, Sherlock or Daddy read to her. Daddy does all the voices in stories, and Sherlock can turn his reading voice deep and slow in a way that makes Rosie sleepy by magic. Or if she can’t get sleepy Sherlock sits by her bed and plays violin, or if she has a nightmare then Daddy cuddles with her and lets her sleep with the lights on.

 

That’s Rosie’s family and mostly, that’s her life.

 

* * *

 

The second rule is that people don’t say what they mean, mostly, so you’ve got to pay attention to everything else if you want to know what’s true.

 

Uncle Mycroft teaches Rosie this rule sometimes when he’s in charge of her, which isn’t very often. One of the times that he is, Rosie’s sitting reading a new picture book in Uncle Mycroft’s office when a man with an accent bursts in to talk with Mycroft. Except he keeps stammering and pretending not to look at Rosie and until he manages to ask, “Who is the child?”

 

“Younger cousin,” Uncle Mycroft tells him, smoothly. Uncle Mycroft lies to people a lot but he’s allowed because he’s a grown-up. Whenever he lies about Rosie, she’s meant to play along, because the first rule of being with Uncle Mycroft is that she must do as she’s told and questions later. 

 

(One reason she likes Uncle Mycroft better than most grown-ups, and better than Sherlock says he wants her to, is because Uncle Mycroft answers questions for real when Rosie asks them. So does Sherlock, but Rosie doesn’t tell either of them that because they pretend not to like each other.)

 

“What’s your name, little one?” the man asks Rosie.

 

Rosie hides her face in her picture book like she’s shy, which she’s not really. Plus Rosie’s not sure if she’s meant to have a pretend name or not so she thinks it’s better not to say anything.

 

“Tell the nice man your name, Mary,” Uncle Mycroft says to Rosie the way grown-ups say to little kids who are too shy to say their names. 

 

It’s dead clever because now Rosie knows her pretend name is Mary, and now the man thinks Rosie’s called Mary, and Uncle Mycroft sounds a little bit like he wants to sigh about pretend Mary being shy so that means Rosie should keep being pretend shy which means that Rosie shouldn't talk much.

 

Rosie mumbles, “Mary,” from behind her book, and the best part is it’s not really a lie because Rosie’s second name is Mary, because it was her mum’s name except Mum was also called Rosamund because Mum was sort of confusing.

 

“How old is she?”

 

Rosie sticks up fingers for how old she is but adds one because they’re playing pretend. Uncle Mycroft squints a little at her, but he’s very serious about playing pretend so he doesn’t say anything about it.

 

The man talks to Uncle Mycroft some more about grown-up things and Rosie mostly ignores them and reads her picture book. Before the man can leave Uncle Mycroft leans in very close and says something quietly; all Rosie can hear is her pretend name. It makes the man look like he ate something that’s gone off; he leaves almost as fast as he came in. 

 

“You did well, Rosamund,” Uncle Mycroft tells her afterward, which means they’re done playing pretend. “You kept your head.”

 

“It’s right here,” Rosie says cheerily, pointing at her head to make Uncle Mycroft roll his eyes. It’s really really easy to be pretend annoying to Uncle Mycroft, which is probably why Sherlock loves doing it.

 

“You knew what I meant.”

 

“I know. Why did we pretend I was Mary?"

 

"You tell me."

 

That's exciting, Uncle Mycroft doesn't make Rosie deduce as often as Sherlock does. Sherlock says it's because Mycroft isn't patient and likes to show off but Dad says there are toddlers more patient than Sherlock and who is Sherlock to talk about showing off anyway. Rosie does her best thinking face. "Cos of you didn't want him to know who I am really. You said younger cousin and not niece so, so I'm a  _secret_?" That's brilliant, it's like she's a  _spy_. 

 

"Not entirely wrong. Rosamund, because of my position in the government–"

 

"Being it?"

 

"–because of the sensitive _role_ I play in government, there are some people who do not care for me or who would use those close to me to make me do things I otherwise would not."

 

"But not him, right?" asks Rosie.

 

Mycroft does the same eyebrow at her that Sherlock does when he thinks Rosie is clever. "Correct. Tell me why not."

 

"You wouldn't let him come in your secret office and see me if he was a bad guy for real. Or I guess Anthea wouldn't let him come in, cos she's at the door and she's a ninja."

 

"You are correct in that I would not expose you to anyone who has ill intent. Still, even in the case of that idiot, it is more prudent – do you remember what _prudent_ means? Good. It is more  _prudent_ to conceal our true connection so the man cannot accidentally let information slip to those you call  _bad guys_. I would never put you at risk, Rosamund."

 

Rosie gives him the biggest smile ever because Uncle Mycroft saves hugs for special occasions. He says something like "Yes, well," and taps his fingers on the desk.

 

"Where was his voice from?” Rosie asks. "The idiot who wasn't a bad guy."

 

“His _accent_ was Slavic. Ukrainian, specifically. Do you remember where Ukraine is on the map?”

 

Rosie scurries over to the map Uncle Mycroft pulls onto his desk and stares at it. Uncle Mycroft thinks it’s very important for Rosie to know geography. Sherlock says that’s because Mycroft basically runs the world. Daddy says it’s because Mycroft doesn’t want Rosie to grow up without knowing basic things, like countries or the solar system or who’s the Prime Minister.

 

Rosie doesn’t point out Ukraine on her first try but she’s close. “Second guess!” cheers Rosie. 

 

"Well done, Rosamund," says Uncle Mycroft, and she knows he means it.

 

* * *

 

This is how Sherlock and Daddy work together:

 

A case happens and Sherlock does deductions. Dad will suggest things so Sherlock can say why Dad’s right or wrong (mostly it’s wrong). Dad’s way of thinking about things helps Sherlock think better about things and be even more of a genius. Then they solve the crime and Dad blogs about it. Sometimes there’s danger in the middle but Dad says that he and Sherlock are really good at not dying.

 

“Sherlock died one time,” Rosie says to that, just pretending to be a little bit annoying. She knows it was fake dying but everybody thought Sherlock was dead, so. That’s when Rosie’s dad met her mum.

 

Sherlock must have been thinking the same thing because from next to her in the cab he says, “Yes, and you wouldn’t be alive if I hadn’t done, so really you ought to thank me.”

 

“Sherlock,” scolds Daddy from her other side, but lightly because he knows Sherlock’s just pretending to be annoying too.

 

Daddy says Sherlock thinks better when there’s people around. Sherlock says that Dad’s wrong and that Sherlock thinks better when there’s a _Watson_ around. Rosie asks did that include her mum and Sherlock says obviously and Dad says that Rosie’s mum was nearly as smart as Sherlock and that meant Dad was on double-duty to _two_ mad geniuses, so thank God Rosie was born to help Dad out. 

 

Rosie tells Sherlock, “So that means you think best when we’re both on cases with you.”

 

Sherlock makes his voice sound more bored, which means Rosie had surprised him saying something to do with feelings. “I suppose it does, yes.” 

 

“So Daddy,” Rosie adds, turning her head to her father, “that means you really have to bring me on more cases, so they can get solved better.”

 

“Rosie, you know some cases can be–”

 

“But you _specially_ have to bring me on the dangerous ones cos they’re the ones that need solving the most! It would help loads of people!”

 

Her dad pinches his nose. 

 

“You can’t fault her logic, John.” Sherlock’s voice is a little high like he thinks Rosie’s funny.

 

“Also, also Daddy, then you could do a blog about me too. And I could have 2015 for numbers on the side like you’ve got 1895.”

 

Dad opens his mouth but Sherlock blurts out, “Watson – are you saying you think your father was born in 1895?”

 

“Is Daddy or you? It’s Dad’s blog but it’s of you so I wasn’t sure which.”

 

Now they’re both laughing, so Rosie scowls. “I wasn’t being funny!”

 

Daddy’s still laughing when he puts an arm around her as the cabbie does a turn onto Baker Street. Speedy’s is lit up for evening and Rosie crosses her fingers that she’ll be allowed a sandwich from it even though they’re coming from Angelo’s where Sherlock and Dad go after cases. 

 

Rosie doesn’t know if Sherlock’s noticed her crossed fingers yet like she’d hoped, when Dad says: “We ought to work more on your maths, Rosie. What age would I be if I’d been born in 1895?”

 

“That’s too much maths.” 

 

“So do it on paper in the flat,” suggests Sherlock. “And we won’t buy you a sandwich when you’ve just had Angelo make you dinner for no charge.”

 

“But we never pay at Angelo’s and it’s just one sandwich, I’m still hungry.”

 

“I can’t understand it,” Sherlock mumbles. He’d barely eaten any of his dinner, as usual, so Rosie got his breadstick. 

 

“One of them won’t eat,” says Daddy, “and one of them will eat us out of house and home. Christ, I’m beset on all sides. You paying the fare, Sherlock?”

 

That’s a sort of joke Dad says every time their cab stops at 221, because by the time Dad’s done saying it Sherlock’s always swept out onto the curb. Sherlock beckons Rosie out after him and hoists her up in his arms while Dad pays the cabbie. 

 

“Add five years to 1895 and it makes 1900,” Sherlock tells her. “It makes the maths easier. One hundred years from 1900 to 2000, then add which year it is now from 2000 onto one hundred, then add five.”

 

Rosie squints at him. “You were saying too fast, Sherlock.”

 

He says it again slower and then Rosie gets the maths straight in her head. “That’s loads older than even Dad.”

 

“Yes, thank you, Rosie,” Daddy says when he’s done paying. She sees Sherlock wink at Dad as she reaches down from Sherlock’s arms to open the door of 221. 

 

* * *

 

Rosie learned how to count on the steps to 221b when she was very little. Sherlock would hold her hand and they’d recite _one, two, three,_ for each step all the way to seventeen. When they reached the top they’d do three extra stomps for _eighteen, nineteen, twenty_ ; the numbers after that were easy, just a repeat of the stair numbers with different names on the front. 

 

She learned to read by accident when she was little, too, because of Daddy and Sherlock reading to her all the time. Daddy always put his finger under the words he was saying, and Sherlock always explained words he knew Rosie didn’t know, and then one night when she was read to Rosie realized she could read along and that was that. She wasn’t very good at remembering how to spell words but she was getting better so that was okay. 

 

Rosie was ace at science because she did science with Sherlock all the time, and because Dad was a doctor and her mum had been a nurse. “It’s in my _genes_ ,” Rosie often said at school, mostly to impress her teachers.

 

But Rosie still couldn’t do her _stupid_ shoelaces, even though she understood _how_ to: her stupid fingers just wouldn’t _listen_ to her stupid brain. 

 

“It just takes practice,” Dad told her. “Rome wasn’t built in a day, you know.”

 

“Could’ve done if they din’t have to do their stupid _shoelaces_ ,” sulked Rosie. 

 

Sherlock said, “Romans wore sandals, Watson.”

 

Rosie dropped her other trainer. She _loved_ wearing sandals. “ _Really_? Like _always_? That’s the most amazing ever – Daddy, Sherlock, I’m abicating.”

 

“You’re what?” asked Daddy.

 

“Like the Queen’s uncle. I’m gonna be Roman so I can wear sandals.”

 

Dad pinched his nose but also chuckled. “You mean _abdicating_.”

 

“Actually,” said Sherlock, “you mean _emigrating_. But also what John said.”

 

“I’m _emigrating_ ,” Rosie went on staunchly. “I’m Roman now. Bye, shoelaces.” She kicked her trainer under Sherlock’s sofa and started to pull off the other one when Daddy picked her up and tipped her upside down. 

 

“Romans,” Daddy said between Rosie’s giggles, “didn’t wear sandals when they got to _Londinium,_ especially not if it’s _thirteen degrees_ and they’re going to the park with their old dad and their enabling godfather.”

 

“I am only stating the facts,” complained Sherlock. 

 

“Daddy!” Rosie shrieked, and he swung her onto his hip. She reached over Daddy’s shoulder to grab at Sherlock’s collar. “Sherlock, Romans didn’t have _godfathers_.”

 

“Not until Catholicism, no.”

 

“We’re not Catholic,” Rosie pointed out to her dad.

 

“Nope,” Dad said cheerfully. “We’re heathens, who are going to the park with our proper shoes on and no one is abdicating or emigrating.”

 

“Okay _fine_ ,” sighed Rosie, and Dad sat her on the sofa so she could watch keenly as Sherlock did her shoelaces.

 

* * *

 

Molly and Rosie spend at least one day a week together just the two of them on account of Rosie needing a female role model since she hasn't got a mum.

 

“Mrs Hudson’s a female,” Rosie informed Molly on one of their days out. 

 

Molly smiled in the soft way she had and swung their clasped hands. “That’s true! You know, really it's just my excuse to spend time with my favorite little girl.”

 

“I’m not little,” Rosie said automatically.

 

“Well, you're growing up a lot faster than I’d like, would you mind slowing down a little?” teased Molly. Rosie grinned because Molly sounded like a mum when she said things like that. People always thought Molly was Rosie's mum when they were out together; Rosie liked that.

 

Molly was the one who went shopping for clothes with Rosie; Daddy always said Molly didn’t have to and Molly always said that Dad’s jumpers tell her she must. (Sherlock wasn’t allowed to buy clothes for Rosie except on special occasions because Daddy said Sherlock would spend a million pounds on Rosie every day until there was no money left in the world and Rosie was spoiled rotten. Rosie doesn’t think that sounds so bad, but it’s just one of Daddy’s rules.) Rosie hated having to try on clothes to see if they fit, but Molly would play that they were doing a fashion show or that Rosie was a spy being different people in each outfit, and that made it fun.

 

Other times Molly took Rosie to the zoo, or a museum doing a children’s program, or to the part of hospital where Molly worked but not when there were dead bodies out. The best was when Daddy and Sherlock wanted a weekend for a case or for having time to themselves and Rosie got to stay over at Molly’s flat. Molly had all the cats in the world, probably, and Rosie got to play with them for hours and hours while Molly made healthy food in her kitchen because she says everyone at Rosie's is going to turn into a takeaway container if Molly doesn't take immediate action.

 

One afternoon at Molly’s, while Molly made them yogurts with bits of fruit and granola and honey on them and Rosie tried to fit all the cats in her lap at once, Molly asked Rosie, “Do you remember when you were little and you called Mrs Hudson Ma Hudders?”

 

“Yeah!" Rosie laughed. "Why did I do that?”

 

“I think Sherlock had you saying it. He was always teaching you to say funny things. It was sweet, though, little baby Rosie going down the stairs on her bum calling ‘Ma Hudders!’ so Mrs Hudson would know you were coming down for a visit.”

 

Rosie thought for a moment. “I dunno why I call her Mrs Hudson now and not that.”

 

Molly came over to the sofa balancing two bowls of yogurt. “Well, everyone around you calls her Mrs Hudson. I suppose you picked up on it.”

 

“I guess.” The yogurt was delicious. Normally Rosie wasn’t keen on yogurt but Molly made it taste good by magic. Molly always knew how to make things good because Molly had always been there, ever since Rosie was born. Molly had taken care of Rosie when Rosie’s mum died and she’d never stopped taking care of Rosie.

 

Rosie asked, “Did I ever call you Mum?”

 

Molly’s eyes got huge in her face. "What?"

 

“When I called Mrs Hudson Ma Hudders cos I was little. Did I call you Mum when I was little, too? Because you’re basically my mum and Mrs Hudson’s basically my gran and people call their grans all funny things sort of like Ma Hudders so–”

 

Then Molly hugged Rosie so hard that Rosie almost dropped her yogurt. Even when she tried telling Molly that, Molly didn’t let go. 

 

“I would never want to replace your mum,” Molly told Rosie softly. “Your mother loved you so much, Rosie, and she’ll always be your mum–”

 

“I _know_ ,” mumbled Rosie, because grown-ups  _always_ said that to her. “I just wanted to know, if when I was little I thought you were my mum, because you always take care of me and do all the mum things and anyway you’re my godmother, so that makes you a kind of mum, right, Molly?”

 

Molly started sobbing into her yogurt and only got louder when Rosie tried to wipe Molly’s tears with a napkin. Rosie started getting worried that she'd hurt Molly's feelings but Molly managed to say that no, she wasn't sad, it was very happy crying because she loves Rosie very much.

 

" _Happy crying_ ," Rosie whispered to herself while she and Molly hugged for basically an hour. Rosie had thought crying was always sad. The world was full of feelings.

 

* * *

 

Rosie's mum had a thing about making videos. There’s a Mum video for every one of Rosie’s birthdays basically until forever. Rosie doesn't know how Mum had the time since she died when Rosie was a baby. Daddy and Sherlock have seen all Mum's videos but Rosie waits for her birthdays, when they watch that year’s video together. 

 

On Rosie’s last birthday the Mum video said mostly the same things as always, like how Mum loves Rosie always and is very proud of her and glad to have been her mum. Mum had curly blond hair like Rosie does but cut short like Sherlock’s, and she smiled with her whole face. 

 

Then on the screen Mum said how happy she was that Rosie was getting to be such a big girl – and for the first time in a Mum video, Rosie’s mother suddenly looked very sad. “I wish I could have known you as you get older,” Mum in the video said to Rosie in real life. “I wish I knew the person you were becoming. But I know you’ll be – amazing, Rosie. Absolutely amazing.”

 

Rosie didn’t feel amazing; mostly she felt like she was crying tears for more feelings than had names and trying to hug Daddy and Sherlock at the same time.

 

* * *

 

The third rule is that you have to notice absolutely everything with your eyes _and_ your brain. It’s an especially important rule because you never know what little thing might be important later.

 

Rosie’s a great noticer. Daddy always says that he can’t get away with anything anymore, which is a joke because Sherlock has been noticing all the things about Dad since they met at St. Bart’s a million years ago.

 

Sherlock always does a proud face at Rosie’s noticing except when she’s noticed that he’s snuck a cigarette (smoking is against the rules). Then he looks like he’s swallowed something sour.

 

“It’s because he’s glad you observe things so well,” explains Daddy, “but he’s finally realizing it’s not always fun to be the one getting looked at. Serves him right,” Daddy adds fondly.

 

Rosie’s not so good at understanding what the things she notices _mean,_ but she’s learning all the time from Sherlock. That’s the part he’s best at, really.

 

“Do the woman by the till,” Sherlock suggests one afternoon at Speedy’s. 

 

Rosie peers carefully at her. “Er, she’s grown-up but not as much as you and Daddy. Black jacket and jeans but not tight ones. She has her face done up a lot and a laptop bag. And she got some black on her hands. Hand, I mean, just the right one. Um, she hasn’t got a ring on her finger but she’s got a big one on a necklace, that’s funny. I think her watch is backwards. Her hair’s in a bun.”

 

“Tell me about her fingernails.”

 

“Uhm, short? No nail varnish. Not short like mine like she bites them. Short like how Daddy has all short fingernails.”

 

“Good, good. Now try putting it all together. What can you _deduce_ about her?”

 

Rosie scrunches up in her seat like Sherlock does and thinks, and thinks. “Maybe she’s in uni?”

 

“Why do you say that?”

 

“Cos of she’s got a laptop in her bag with loads of paper and a big book. And she’s grown-up but not old and she looks cool and has makeup but her face is tired, the things under your eyes?”

 

Sherlock smiles at her. “Correct. Well done, Watson.”

 

“What else?” asks Rosie excitedly, because there’s always something.

 

Sherlock takes a deep breath. “The ring on her necklace is the kind worn by graduates of specific universities, but it’s an old ring – well-kept, but from at least one if not two generations above her. Wearing it on a necklace means it’s significant to her, so likely a parent or grandparent’s. Even more likely since she wears the ring on display it belongs to the university she attends, which would be the same one as the family member I mentioned, she’s probably studying what they did or near to it. Her hair’s back, but she’s not just done it up loosely to keep it from mussing in the wind: it’s high and tight, practical, no hair falling in her face. Black ink on her hand suggests frequent writing but poor penmanship so she’s likely a more tactile learner, retains information more clearly when she’s taking notes in longhand than on a keyboard but still requires a laptop for her courses. Add it all to her watch, purposefully fastened backwards, yet she initially glances at her outer wrist when checking the time – she’s not used to wearing her watch that way but is determined to get in the habit. Why?”

 

Rosie stares at Sherlock like he’s telly. “Um, to be like the Doctor from before he was Scottish?”

 

“Delete that show,” Sherlock tells her. “It has no logical consistency or relation to reality whatsoever.”

 

“Daddy says you don’t like it cos sometimes you guess the endings wrong,” says Rosie. 

 

“The _point_ is,” Sherlock interrupts, “it’s common for nurses to wear their watches the wrong way round. It makes it easier to take a patient’s pulse.”

 

Everything falls into place. “She’s at uni to be a nurse!” cheers Rosie, too loudly. The student nurse frowns over at them and opens her mouth but doesn’t say anything.

 

Sherlock does his normal people voice and says, “Sorry, so sorry.” They leave fast. 

 

“But she is, isn’t she?” Rosie asks outside of Speedy’s. It’s still awfully windy outside so Rosie burrows into Sherlock’s coat like it’s a curtain, and he lets her even though it’s about four steps from Speedy’s to the door of 221.

 

“She certainly is,” nods Sherlock. “Well done, Watson. Your acuity is far beyond the norm for your age bracket.”

 

Rosie says, “ _Cool_ ,” and wonders what acuity is as they step inside, out of the wind.

 

* * *

 

Sherlock has a weird friend who texts him sometimes. Rosie’s not really meant to know about her, but once Sherlock’s mobile was on the table when it sighed really loudly and Rosie saw he’d gotten a text from – what woman? – before Sherlock snatched it away to slip in his pocket.

 

“Aren’t you going to text her back?” asked Rosie. 

 

Sherlock twisted his face up. “I rarely do. She doesn’t expect it.”

 

“Why not?” 

 

“She’s not actually interested in my replies, she just wants to remind me she exists.”

 

“Why?”

 

“Because I saved her life once,” Sherlock sighed, “and she’s insufferably smug about it.”

 

“Oh,” said Rosie. Sometimes she forgot that when Sherlock and Daddy save people’s lives those people are actually real, not just part of the blog or the papers. “Was she a case?”

 

“Not exactly.”

 

“So why did you save her?”

 

Sherlock – who’d been staring in his microscope the whole time – looked over at Rosie. 

 

“Because she tricked me,” he told her finally. “Of course, I tricked her back afterwards. But she tricked me first, and most people can’t manage that. We hold one another in a sort of mutual regard.”

 

“Oh,” Rosie said again, and thought for a moment. “Does that mean she’s your friend?” The woman didn’t sound that friendly, really, but Sherlock’s got all weird friends.

 

Sherlock’s _mmm_ turned into another _not exactly_. “She’s not _not_ a friend. But she’s not someone I’d ever let meet you. To be perfectly honest I often do forget she exists if she’s not texted for a while. And she’s nothing next to your father.”

 

Rosie didn’t know why Sherlock said that last bit, but it was nice to hear.

 

* * *

 

Sometimes on weekends or holidays Rosie gets to go with Dad and Sherlock on cases for clients. Even though she’s not allowed to see dead people at crime scenes or in Molly’s hospital, it’s always brilliant. Except when they’re at the Met while Sherlock talks at Uncle Greg and Rosie just has to sit around, that’s dead boring.

 

It’s fun to see Sherlock turn into Sherlock the Consulting Detective and Dad turn into Doctor Watson (like Rosie’s seen him do at the surgery) with a little Captain Watson (who Sherlock says Dad is when there’s danger). 

 

The best bits are when Sherlock has Rosie help for a case, like when she played football in the park with a boy so Sherlock could pretend to be Rosie’s uncle and talk with the boy’s mum but secretly deduce her. 

 

Or when they were pretend American tourists at the Tower of London. Sherlock wore jeans and did an accent because someone had disappeared on their tour in the White Tower. Rosie just pretended that she was shy because Sherlock said her American accent was a good start but needed practice. After that, Rosie wanted to see the crown jewels so they did, but Sherlock kept on mumbling about the bad guy Moriarty instead of looking.

 

“What happened to the princes for real?” Rosie asks Sherlock when they're leaving the Tower and aren’t pretend Americans anymore. “The White Tower ones. _Were_ they murdered?”

 

Between quick texts on his mobile, Sherlock tells her, “They were certainly disposed of in some way. Murder seems most likely; usurpers generally prefer to be as thoroughly rid of the rightful heirs as possible.”

 

“Is a u-use-usap- what you said, is that like Mycroft being all the government but secretly?”

 

No other girl has a sort-of uncle who’s the government; it’s brilliant. Sometimes Rosie pretends in her head that Mycroft is the secret real king of England and that Sherlock is a prince, because if Sherlock is a prince then Daddy is too and that means Rosie is royal, so she could be a knight. She’s dead keen on being a knight when she’s grown up even though Sherlock keeps telling her knights are boring nowadays. 

 

Sherlock finishes off his text. Then he kneels down by Rosie to explain _usurpers_ and help her say the word better. He’s the best explainer in the world – loads better than the new teacher for her year – and by the time they’re in the cab going home Rosie knows all about how a smart but bitter man in history called Richard probably had his nephews murdered because he wanted to be king instead of them and then Shakespeare made a play about it. 

 

“Oh god, what’ve you taught her now,” groans Daddy back in 221b. That’s what he says when Sherlock’s taught Rosie something interesting but Dad has to pretend not to like it because of rules. 

 

“ _Daddy,_ ” Rosie gushes, scrambling onto Dad’s lap so he has to listen. “Daddy, there were _so many murders_ at the Tower, there were a million beheadings and now there’s a pl-, plac–”

 

From the kitchen, Sherlock calls, “Plaque.”

 

“–on the ground where all the heads got cut off. ’Cept Sherlock says that’s not the real, actual azact spot where they all got killed, it’s just close to it and the tourists don’t care if it’s right really cos they just wanna take pictures with the hat soldiers who don’t move. Oh! Did the, the, I forget his name, did he _really_ break in and sit on the throne with the crown jewels?”

 

Dad frowns. “Did who do what?”

 

“You _know_ , Daddy, the bad guy, when Sherlock died for pretend. Ooh! He pretended he was Richard but he wasn’t, and Richard was the king who probly killed his nephews! _Wow_.” 

 

It takes Dad a moment. “Do – do you mean _Moriarty_?” 

 

“Yes, him. How did he break in to the crown jewels but the hat soldiers didn’t stop him?”

 

Dad blinks at her for a second. Then over Rosie’s shoulder he calls, “Yes, Sherlock, how did he do that? And what exactly have you been telling my little girl–”

 

“M’not little.”

 

“–about your archenemy?”

 

“Mycroft is my archenemy,” mutters Sherlock from where he’s hiding behind his newspaper. 

 

“No he’s not,” Rosie and Daddy say at the same time. 

 

Sherlock lifts the newspaper higher. “Watson is very observant,” he manages. “No doubt she’s absorbed a detail or two about Moriarty simply by living in a flat with us.”

 

“And from the –  _plaque,_ ” Rosie pronounces it carefully.

 

Daddy and Sherlock both look at her. 

 

“At the crown jewels, when you go in, didn’t you see it, Sherlock? There’s a plaque about how it got broken in to by, by the bad guy.” Already Rosie forgot how to say his name correctly. 

 

Now Daddy and Sherlock look at each other. 

 

“I rest my case,” says Sherlock, and turns the newspaper right-side up. 

 

* * *

 

Rosie likes all the police; most of them like her too, but some complain when she comes along on cases. She’s not allowed on crime scenes and she doesn’t _touch_ anything, she just has to wait outside the police tape where it’s _boring_ , but some people are idiots and give each other looks or grumble when they see her.

 

(It’s _stupid_ because Sherlock tells her all the good bits of the crime scene afterward _anyway_ and besides, Rosie’s godmother is a doctor of dead people and Rosie’s dad is a doctor of alive people _and_  Dad used to be in the army. Rosie’s not scared of anything in a crime scene, because she got cool genes.)

 

Sergeant Donovan likes Rosie, though; she answers all Rosie’s questions about what the police are doing unless the answers are things not meant for kids to hear about. That would bother Rosie, except–

 

“Tell you what,” Sergeant Donovan says once when she sees Rosie’s frown. “Write down which cases I can’t explain to you now and ask me when you’re older, if you’re still keen. I’ll tell you about them then.” 

 

“Really?” Sergeant Donovan nods. “How much older?”

 

“Oh, eighteen, I suppose.” 

 

“That’s _forever_.”

 

“Sixteen, then, if your dads don’t mind your hearing about them a bit younger.”

 

Rosie doesn’t call Sherlock _dad_ (that’d be confusing since Dad is dad) but sometimes people assume she calls him that so Rosie doesn’t say anything about it. “Sherlock won’t mind but I dunno about Daddy.” 

 

Sometimes Dad’s not bothered by Rosie knowing grown-up things, like how Dad’s got a massive scar on his shoulder from being shot at when he was a soldier, or how Rosie’s mum died because she let herself be shot so Sherlock wouldn’t be. Once Rosie heard by accident that when Rosie’s mum was pregnant she’d shot Sherlock so Sherlock wouldn’t die, or something. People get shot an awful lot in Rosie’s family.

 

Sergeant Donovan starts to say something about Sherlock but then closes her mouth. Rosie remembers that Sergeant Donovan and Sherlock used to not like each other for real but now they just pretend to not like each other. Daddy says that Sergeant Donovan warmed up to Sherlock because she could tell Sherlock loves Rosie, and that Sherlock stopped acting mean to Sergeant Donovan because it was a bad example for Rosie. That means that Rosie is a good influence on Sherlock and Sergeant Donovan, which is a very grown-up thing to be.

 

Rosie likes being at crime scenes better than being at Scotland Yard, because it’s just a load of offices for the boring bits of cases. Rosie tells that to Uncle Greg once and he shrugs. 

 

“Not entirely, poppet. And the boring bits are important, no matter what Sherlock says.”

 

“I know,” Rosie nods. “Sherlock thinks loads of things are boring that are actually important. Like doing the washing up. And knowing who’s prime minister.”

 

Uncle Greg laughs. “You’re a wise one, aren’t you?”

 

“I am very wise,” says Rosie. “I get the best marks except for in spelling. And I can find everywhere on the map on mostly my first try.”

 

Uncle Greg agrees that Rosie’s map skills are very impressive. 

 

Uncle Greg is one of Rosie’s favorite grown-ups because he always takes Rosie seriously. One time when Rosie was little she saw Mrs. Turner’s cat eating a bird and Rosie called Uncle Greg on her emergency mobile crying that the cat had to go to jail because it was a murderer. Uncle Greg said he’d never arrested a cat before and didn’t think it was his division. Then he said even though it was a shame about the bird, the cat was only being a cat and doing what nature meant for it to do, like how lions hunted antelopes and all that. 

 

Uncle Greg didn’t explain things as well as Sherlock but he made her feel better anyway.

 

* * *

 

Rosie asks Sherlock first, because Sherlock doesn’t care about rules as much as most dads do. Sherlock doesn’t really care about rules much at all, except the ones Dad’s most keen on and the ones that keep Rosie from getting hurt and the most obvious rules like don’t kill someone unless they’re trying to kill you first, then you’re allowed to kill them back. 

 

Rosie’s going to ask Dad after Sherlock, but Dad’s at the surgery this afternoon so it’s just her and Sherlock. They’re timing how fast different bits of cloth dissolve in acid. It’s the perfect time because Sherlock does better at talking when he’s also doing another thing, or if he’s not made to look completely at you. They’re both looking hard at the experiment on the kitchen table – because Sherlock’s about to drip another bit of acid on a cloth sample – when Rosie finally pushes the words out of her mouth. 

 

“Tell me about Mum?” It wasn’t meant to be a question but Rosie got nervous halfway through. 

 

Sherlock only moves a little bit. Then he drips the acid onto the fabric and Rosie does her job which is starting the timer.

 

“You’ve been asking about her more often, you know.” 

 

The funny thing was that Rosie’d heard Daddy and Sherlock saying the same thing to each other a few days ago and that’s why she’s asking now. Rosie hadn’t noticed she’d been asking about her mum more, but once the thought was in her head she realized she _would,_ actually, like to know a bit more about her mum. 

 

Listening in had given Rosie the fuzzy idea that her mum hadn’t been a normal person like other people’s mums, even other people’s mums who were also dead. Because before she was Rosie’s mum, she was something for the quietest voices. 

 

“Was Rosamund her middle name?” Rosie blurts. It’s not exactly what she wants to ask, but she’s also sort of confused because her mum’s name was Mary Morstan and then Mary Watson and she’s not sure how Rosamund fit in. 

 

“No,” says Sherlock. “Her name was Rosamund Mary, like you.”

 

“Oh.” Rosie thinks for a second. “But you and Daddy both said she was just called Mary. Even though she was also Rosamund.”

 

Sherlock hesitates. “She kept the name Rosamund a secret until after you were born.”

 

“Why?”

 

Sherlock turns and looks at her from behind his goggles, which surprises Rosie. The uncomfortable tickle in her stomach makes her wonder if  _she_ prefers having talks without needing to look at people just as much as Sherlock does. 

 

“There were things from her past that she wanted to put behind her. That meant leaving behind her old name.”

 

Part of Rosie burns to ask _what sort of things_ , but she knows, really, or knows enough – things you whisper about as quietly as you can, so you’re sure no one will hear them even if they’re listening in. You don’t whisper like that for good things. 

 

“But why did her name have to be a secret?”

 

“Sometimes people think having secrets from those they love will keep their loved ones safe. Your mother wanted to keep you and your father safe more than anything else, Rosie.”

 

Sherlock calls her _Watson_ a lot of the time or sometimes  _my dear Watson_ or even  _Rosamund_ since no one else uses it. _Rosie_ is special for when there are feelings; it’s like Sherlock saying he never deletes anything about her. 

 

“But it was only her name.” My name too, thinks Rosie. “It wasn’t a, a murder or something.”

 

Sherlock does a bit of a slower blink and then says _no_ with slow _n_ ’s. “It was who she was – before – and she wanted to be someone else. She wanted to be Mary Watson, so she was. Stop the timer.”

 

She’d forgotten about the timer but her fingers press the button anyway. Her brain’s too busy with all the thoughts that keep bumping into each other and breaking off bits. Words fall out by themselves–

 

“But she – but if she – if she was _bad_ when she was my name, my mum, then why did she name me her name?”

 

Even Rosie’s not sure she understands what she’s asking but she knows that Sherlock will. Sherlock always understands. That’s why he pulls Rosie’s goggles off and draws her to his side and doesn’t complain when she tangles the tassel of his robe in her fingers. 

 

“I can only deduce,” Sherlock tells Rosie. “We never asked her why. Perhaps she wanted you to understand that everyone she ever was belonged to you, because she loved you. Perhaps she wanted the name to have a second chance with you. Perhaps she wanted you to feel like the two of you had a secret together, a connection, both being Rosamund.

 

“Watson,” he says, quietly now, “you don’t have to understand any of this now. You can keep on understanding it bit by bit your whole life, if you want to. What matters in the end is that she was your mother, Rosie, and she loved you with all she was.”

 

“Like you and Daddy,” Rosie says into Sherlock’s robe. And Molly, and Mrs Hudson, and Mycroft even, she thinks. They're all Rosie's and she's theirs – so maybe it's okay, whoever Mum was, whatever their name means.  _Rose of the world_. Rosie's world is the best people, and she loves them and they love her. 

Sherlock's gone very still. Rosie hugs him harder to make him move and then he's hugging her back.

 

After a moment Sherlock says, “Yes, like that.”


End file.
